Time that an infant spends in prone (laying with their tummy down) to strengthen their muscles.
Why is it important?
Since most babies are put "back to sleep", infants are spending much less time on their stomachs. Some babies spend so much time on their back that their head becomes flattened and they become delayed/ or miss some developmental milestones all together. (No crawling)
Giving an infant as much time as possible (during waking hours) on their stomach, creates more opportunities for strengthening muscles, weight bearing and exploring their environment (both sensorially or cognitively).
But...My baby hates it.
Start it as a newborn.
If it's too late for that, make it a game.
Lay your baby on his/her tummy near the edge of the bed, arms in front like a push up. Now while staying close (so you can keep baby from wiggling off) sit on the ground next to your baby. Talk, sing and play with your baby.
You can also try propping up your baby on a boppy while playing, shaking a toy.
Put a makeup mirror in front of your baby. Infants love to coo and play with their reflection.
Start small. 2-5 minutes, 10 times a day. Then build up. 10-15+ minutes, 3-5 times a day.